Gel-forming inspection penetrant and emulsifier compositions and processes



Oct 24. 1967 J. R. ALBURGER 3,349,041

EMULSIFIER GEL-FORMING INSPECTION PENETRANT AND COMPOSITIONS ANDV PROCESSES Filed OC. 18. 1965 United States Patent Giiice 3,349,04l Patented Oct. 24, 1967 3,349,041 GEL-FORMING INSPECTION PENETRAN'I' AND EMULSIFHER CMPOSITIONS AND PROCESSES James R. Aiburger, 5007 I-lillard Ave.,

La Canada, Calif. 91011 Filed Oct. 18, 1965, Ser. No. 497,058 Claims. (Cl. 252-3012) This application is a continuation-in-part of application, Serial No. 348,273, filed February 28, 1964, now abandoned for Penetrant Inspection Compositions and Processes.V i'

The present invention relates to penetrant inspection processes, and more particularly to improved penetrant flaw tracer compositions and emulsier compositions; and to improved penetrant inspection processes utilizing said compositions.

Penetrant inspection processes have been well known in the prior art and have had as their purpose the detection in test bodies of extremely small surface discontinuities and subsurface flaws having surface openings. The test bodies, or parts, may be constructed of metal, ceramic, or other material. The known processes have involved nondestructive inspection penetrant testing procedures, with the usual procedure including, as a first step, the immersion of the test bodies in a penetrant aw tracer liquid having dissolved therein either a fluorescent dye or a nonfluorescent visible dye. The penetrant flaw tracer liquid usually employed has been formulated of an oily liquid vehicle (such as refined kerosene or base oil), within which vehicle the dye is dissolved.

After immersion of the test bodies in the penetrant liquid for an appropriate dwell period, the test bodies are withdraw from the liquid and are then subjected to draining, emulsication, and washing operations, for the purpose of removing any penetrant liquid adhering to the surfaces thereof. Minute entrapments of the penetrant liquid, however, remain in any surface discontinuities or subsurface flaws having surface openings, even though extremely small. If the penetrant liquid employed contains a fluorescent dye, the entrapments may be rendered visible by exposure of the surfaces of the test bodies to ultraviolet radiation. If, on the other hand, the penetrant liquid contains a nonfluorescent visible color dye, the entrapments can be viewed in ordinary light.

Two major types of penetrant inspection processes have been utilized. In the case of the so-called post-emulsier type of penetrant inspection process, the penetrant inspection liquid is removed from the surfaces of the test bodies during the washing step through the use of water together with a suitable emulsiiier composition. In accordance with the so-called self-emulsiable, of Water-washable, type of penetrant process, the oily vehicle of the penetrant aw tracer liquid is compounded together with one or more detergents. As a result, upon contact with Water, the penetrant liquid forms an emulsion. Consequently, after the test bodies have been immersed in the penetrant liquid, they may simply be rinsed in water, whereupon the surface penetrant liquid becomes emulsied and is removed without the use of a supplementary emulsier composition.

The conventional oil-phase penetrant liquids of the water-washable type, as well as the oil-phase emulsiliers employed in the conventional post-emulsier penetrant processes, present a number of disadvantages in use. First- 1y, the emulsions which form during the washing step are often not completely stable, so that, as a result, oil and water phase separation often occurs, leading to a reprecipitation of nonemulsied materials on the surfaces being cleaned. Secondly, the presence of the oily reprecipitated residues, not being again soluble in water, may

lead to undesirable effects, such as intergranular corrosion, or chemical reactivity in the case of test bodies used in liquid oxygen systems.

As a further disadvantage of a water-washable penetrant of the conventional type, such materials can provide a high level of flaw entrapment efficiency only if the solubilizing strength of the detergent system employed is just sufficient, and no greater, to render the oily component of the penetrant liquid emulsifiable in water. If the solubilizing strength of the detergents used is too great, the flaw entrapments are too readily emulsiiied and substantial portions thereof may be removed from the flaws by the water employed during the washing step. In view of the relatively low solubilizing strength of the detergent systems utilized, the known water-washable penetrants have often presented problems with regard to reprecipitation and emulsion instability.

With respect to emulsifier compositions which are employed for the removal of oily residues of water-insoluble penetrant or other water-insoluble surface contaminants, it is again found that excessive activity or solubilizing strength of conventional emulsiers can act to strip out small entrapments of penetrant to an excessive degree. The known emulsier materials have often presented problems with regard to flaw entrapment efficiency, emulsion instability, and economy in use.

It is, therefore, an object of the present invention to provide an improved water-washable penetrant flaw tracer composition.

Another object of the invention is to provide a waterwashable penetrant aw tracer composition which presents features of improved stability of the emulsion formed upon Contact thereof with water.

Still another object of the present invention is to provide water-washable penetrant aw tracer compositions which offer unusually high levels of flaw entrapment elficiency as compared to the penetrant compositions of the prior art.

A further object of the invention is to provide an improved emulsier composition particularly adapted for use in the post-emulsiier type of penetrant inspection processes.

A still further object of the invention is to provide an improved emulsier composition which presents features of high emulsion stability and economy in use.

Another object of the present invention is to provide an improved penetrant inspection process of the postemulsifier type.

Another object of the present invention is to provide an inspection process of the self-emulsiable, or water-washable type.

These and other objects of the invention will be made more apparent in the following description thereof when read in conjunction with the accompanying drawings, in which:

FIG. l is a diagrammatic representation, in cross-section, of a surface aw containing an entrapment of a water-washable inspection penetrant of the invention;

FIG. 2 is a diagrammatic representation, in cross-section, of a surface llaw containing an entrapment of a water-insoluble penetrant emulsiiied with an emulsiiier of the invention;

FIG. 3 is a graph illustrating the viscosity characteristics of emulsifier compositions plotted as a function of percent added water; and

FIG. 4 is a graph illustrating the gel-break and solubility characteristics of compositions of the invention.

In accordance with the present invention, there are provided water-washable and normally liquid testing compositions for use in the detection of surface discontinuities in test bodies. Each of the testing compositions comprises, in combination, the following two basic constituents:

phenol; and

(2) A normally liquid Water-insoluble ethoxylated alkylphenol.

In addition to the two ethoxylated alkylphenols, certain of the compositions of the invention may contain supplemental ingredients as follows:

(a) A normally liquid glycol; and (b) An indicator dye.

The water-soluble ethoxylated alkylphenol constituent of the compositions of the invention is any one, or a combination, of the ethoxylated alkylphenols which are normally liquid. Such normally liquid alkylphenols have the following chemical structure:

In the above structure, P is a phenolic nucleus, R is an ethoxy group, and R is an alkyl or polyalkyl chain structure.

For the puropse of this specification, a phenolic nucleus is defined as an aromatic structure containing a phenolic hydroxyl group (or groups), the aromatic structure being any one of the structures; benzene, naphthalene, or diphenyl (biphenyl). It has been found that any one of these three types of nucleii can be monoalkylated, dialkylated, or polyalkylated to form so-called alkylated phenols, and the number of carbon atoms in any given alkyl chain, or R group, may be as low as 5 to as high as 18; that is, for the purpose of this invention. Furthermore, the alkyl chains may occur in isomeric forms, either as straight or branched chains, depending on the mode of synthesis.

The thus-alkylated phenols are condensed with an R group which may consist of from 7 to 15 mols of ethylene oxide per mol of alkylphenol to produce the water-soluble alkylphenols suitable for the purpose of the invention. R may, therefore, be defined as the chemical structure wherein the case of the water-soluble ethoxylated alkylphenols of the invention x may have a value of from 7 to 15.

The water-insoluble ethoxylated alkylphenol constituent employed in the testing compositions of the invention has the same chemical structure as shown above; however,

from zero to 5 mols of ethylene oxide per mol of alkyl-` phenol are here provided, x having a range of values from zero to 5.

An alkylphenol with zero ethoxy content is a special case representing a limiting condition of the water-insoluble class of ethoxylated alkylphenols. As will be explained below, the characteristic behaviour of the water-insoluble ethoxylated alkylphenols depends on the length of the ethoxy chain, and it has been demonstrated that a uniform transition of such characteristics occurs from zero ethoxy content, through fractional values of ethoxy content, up to about 5 mols of ethylene oxide per mol of alkylphenol. Within this range of ethoXy/alkylphenol mol ratios, a preferred ratio is about 1.5 mols ethylene oxide per mol of alkylphenol.

Accordingly, it will be understood that the chemical structures for the ethoxylated alkylphenols, as utilized for this invention, may include the following:

These three types of compounds, all of which may be classed as ethoxylated alkylphenols are well known in the science of surfactant chemistry, although industrial production, in large tonnages, is concentrated mainly on the type (a) structure, and in the monoalkylated 8 or 9 carbon alkyl chain lengths, providing ethoxylated octylphenols or ethoxylated nonylphenols.

All of the above-described ethoxylated alkylphenols behave in a closely similar manner with respect to water solubility, and the degree of Water solubility, in each case, depends on the ethoxy content or mol ratio of ethylene oxide with respect to the alkylphenol portion of the material. This similarity in behaviour permits any of the three types of materials to be substituted, each for the other, in the formulations to be given in this specification, and substantially equivalent gel-forming performance results will be obtained.

Among the ethoxylated alkylphenols which are suitable for the purpose of the invention are the following:

Ethoxylated diamylphenol Ethoxylated octylphenol Ethoxylated nonylphenol Ethoxylated dinonylphenol Ethoxylated trinonylphenol Ethoxylated decylphenol Ethoxylated didecylphenol Ethoxylated undecylphenol Ethoxylated dodecylphenol Ethoxylated octyldecylphenol Ethoxylated diarnylnaphthol Ethoxylated octylnaphthol Ethoxylated nonylnaphthol Ethoxylated dinonylnaphthol Ethoxylated trinonylnaphthol Ethoxylated octylde Cylnaphthol Ethoxylated diamyl p-p biphenol Ethoxylated octyl p-p' biphenol Ethoxylated nonyl p-p biphenol Ethoxylated dinonyl p-p biphenol Ethoxylated octyldecyl p-p biphenol With regard to the glycol, which may be alconstituent of a testing composition in accrodance with the invention, any glycol which is normally liquid is suitable for use. Within the class of glycols which are normally liquid, and thus usable for the purpose of the invention, are the following:

Ethylene glycol Diethylene glycol Triethylene glycol Propylene glycol Dipropylene glycol Tripropylene glycol Hexylene glycol Polyethylene glycol Glycerin Such glycol ingredients may be included in the composition of the invention for the purpose of adjusting the viscosity of the mixture, 'or for extending the volume of the mixture to reduce its cost per unit volume.

Each of the water-Washable testing compositions of the invention may include, `as stated above, an indicator dye. The dyestuff utilized may be in the form of a fluorescent sensitizer or of a visible dye. If a fluorescent sensitizer is employed, a color-former dye may be used in conjunction therewith. Any suitable dye or mixture of dyes may be chosen for the purpose.

Listed below are typical uorescent sensitizers and color-former dyes which have been found to be particularly useful for the purpose of the present invention. The dyes listed have been disclosed in my copending application, Ser. No. 323,529, filed Nov. 13, 1963, for Fluorescent Tracers. These sensitizers and color-formers may be of the water-soluble type or of the water-insoluble type. They are identified in accordance with their standard designations in the Color Index (2d ed. 1956, vol. II) published by the Society of Dyers Colourists, Dean House, Picadilly-Bradford, Yorkshire, England; The American Association of Textile Chemists and Colorists; and the Lowell Technological Institute, Lowell, Massachusetts, U.S.A.

Senstizers V,C.I. Fluorescent Brightening Agent No. 46

C.I. Fluorescent Brightening Agent No. 8

C.I. Fluorescent Brightening Agent No. 69 C.I. Fluorescent Brightening Agent No. 78 C.I. Fluorescent Brightening Agent No. 26 C.I. Fluorescent Brightening Agent No. 68

Color-former dyes Among the suitable noni'luorescent, or visible, dyes which may be employed in accordance with the invention, are a number of red, yellow, and blue dyes, such as the following:

C.I. Solvent Red No. 76 C I. Solvent Yellow No. 13 C.I. Solvent Blue No. 11

The previously identified basic constituents and supplemental ingredients of the testing compositions of the invention may be employed in various concentrations. The glycol ingredient, when used, is preferably employed in a concentration within the approximate range of 20- 45%. The water-soluble ethoxylated alkylphenol is preferably employed in a concentration within the approximate range of 3080% when used in conjunction with a glycol ingredient, and in a concentration within the approximate range of 55-85% when used without a glycol ingredient. The water-insoluble ethoxylated alkylphenol is preferably employed in a concentration within the approximate range of 25% when used in conjunction with a glycol ingredient, and in a concentration within the approximate range of 15-45% when used without a glycol ingredient. The indicator dye, when used, is preferably present in a concentration within the approximate range of (I1-40%.

The water-insoluble ethoxylated alkylphenols which may be used as an ingredient in the compositions of the invention exhibit varying degrees of insolubility, such that the water-insolubility becomes greater as the ethoxy content is reduced, being a maximum when the ethoxy content is zero. Accordingly, it has been found that when the ethoxy content of this ingredient is Zero, its proportional content in compositions of the invention will normally be reduced slightly as compared to that of an ethoxylated alkylphenol ingredient; that is, for similar results. However, the range of concentrations usable will still be about the same as stated above.

In order to properly -understand the unique features of the compositions of the invention with respect to penetrant inspection processes, it is helpful to examine the geometry of a penetrant flaw entrapment and the physical behaviour of penetrant materials as they enter into and exude from surface flaws.

Referring now to FIG. 1, a test surface 5 contains a flaw in the nature of a crack 6. For the purpose of this illustration, it is assumed that a self-emulsiable penetrant has been applied to the test surface 5 so that it has entered into the aw 6, forming an entrapment of penetrant 7. In the washing step of the penetrant inspection process, the surface 5 is washed with water, as indicated by a water layer 8, to remove surface penetrant. During this washing operation, some of the wash water diffuses into the flaw entrapment 7, producing a diffusion zone represented by the lines 9 and 10. At the outer extremity of the diffusion zone, at line 9, there is water present, while at the inner extremity of the zone, at line 10, there is zero percent water present-Between these two extremities, there are found intermediate percentages of water in a water/ penetrant mixture.

At some point inside the above-described diffusion zone, there exists a region, indicated by lines 12 and 13, in which a pronounced thickening or increase in viscosity occurs. Typical water-washable penetrants, as known in the prior art, exhibit a thickening or gel-formation at about 20% added water, and the gel condition persists up to about 50% to 100% added water. Hence, the region indicated by lines 12 and 13 corresponds to a range of water content in the diffusion zone from about 15% up to a maximum of about 50%. Accordingly, it is seen that the portions of the diffusion zone which fall outside the 50% level of water content, as represented by line 13, will have a relatively low viscosity as compared to the portions of the mixture which fall in the gel-zone between lines 12 and 13.

Referring now to FIG. 2, a test surface 15 contains a aw 16, and in this case it is assumed that a water-insoluble oily penetrant has been applied to the test surface 15 so that it has entered into the aw 16 forming an entrapment 17. In order to render the oily penetrant washable in water, an emulsiier composition is applied to surface 15, as represented by an emulsiiier layer 18, whereupon it blends with any oily penetrant present on the surface 15, rendering it soluble in water. During this emulsication operation, some of the emulsiiier diffuses into the entrapment 17 producing an emulsier/penetrant diffusion zone represented by lines 19 and 20. A portion of this penetrant/emulsifier diffusion zone is soluble in water, the soluble portion being that which lies outside a point in the entrapment 17 represented by line 22. The exact position of line 22 in the aw entrapment depends on the emulsiiiability of the entrapped penetrant and the emulsifying capability or strength of the emulsier. In any event, there always exists a point of washability transition, or washability break, in the emulsied flaw entrapment, as represented by line 22.

Now, when water is applied to the test surface, as indicated by layer 23, a condition similar to that illustrated in FIG. 1 is obtained. The emulsier layer 18 and emulsied surface penetrant is flushed away by the wash water, leaving a residual entrapment of material, the outer extremity of which is represented by lineI 24, and then some of the water diffuses into the entrapment 17 to form a diffusion zone, represented by lines 24 and 25. Again, as in FIG. 1, there is 100% water present at the outer extremity of the diffusion zone at line 24, while there is zero percent water present at the inner extremity of the diffusion zone at line 25. And again, between these two extremities, there are intermediate percentages of water in a water/emulsied penetrant mixture.

At some point between -lines 24 and 25, there exists a region, indicated by lines 26 and 27, in which a pronounced thickening or increase in viscosity occurs. It is thus seen that both in self-emulsiiable penetrants, and in emulsifers which are applied to water-insoluble penetrant entrapments, similar flaw entrapment thickening performance characteristics are found. Howe-ver, in prior art selfemulsiiable penetrants and emulsiers, the zones of thickening are found to be well down inside the surface flaws, leaving a relatively large portion of the entrapped material in a condition of low viscosity, permitting it to be readily ushed away in the wash operation. This condition, of course, leads to a relatively low level of llaw entrapment efciency.

Referring now to FIG. 3, curve 30` represents a charting of viscosity of a typical prior art self-emulsifiable penetrant (or emulsifier) plotted as a function of percent added water. As water is added to the penetrant, the viscosity rises and passes through several minor fluctuations, and then rises steeply into a highly viscous condition, represented by point 31. In some cases, the point of maximum viscosity 31 may be well above the top of the graph, such that the material becomes a stiff gel. In any event, the typical prior art self-emulsiliable penetrants and emulsiers all exhibit a sharp drop in viscosity upon the addition of more water, this drop in viscosity occurring at about 50% to 100% added water. For purposes of definition and comparison evaluation between emulsifier and self-emulsiable penetrant compositions, the so-called value of gel-brea in an emulsifier material is the percent added water at which the viscosity passes downward through the viscosity value of 100 centistokes, as indicated by point 32. p

Also illustrated in FIG. 3 is a curve 35 which is a charting of viscosity of a typical composition of the invention, in which viscosity is plotted as a function of percent added water. Here again, as in curve 30, the viscosity rises as water is added, until a stiff gel is formed. However, the mixture remains in a gel condition up to a point well beyond several hundred percent added water, land in some cases the gel-break does not occur until more than 800 percent water has been added.

The important advantage of this broad gel zone, as illustrated by curve 35, can be best understood by again referring to FIG. 1. In FIG. 1, line 13 represents 100% water content in the gel zone. It will be seen that 100% added water to gel-break, such as might be obtained in a prior art penetrant, would actually constitute 50% water content (at gel-break). Hence, for this condition half of the diffusion zone between lines 9 and 10 of FIG. 1, would be ushed away. On the other hand, in a self-emulsifiable penetrant of the invention, which tolerates 800% added water to gel-break, the water content atthe point of gel-break is 89%. Hence, under this condition, the gelbreak line 13- in FIG. 1 is moved out close to line 9 (at the value of 89% water content) so that the washing process removes only 11% of the penetrant/water mixture of the diffusion zone.

It can, therefore, be said that the entrapment efiiciency in washin-g is 50% or less in the case of prior art selfemulsiable penetrants and emulsifers, and in the ran-ge of 89% for the example given of a penetrant composition of the invention. In various examples of penetrant and emulsifrer compositions of the invention, as given below, gelbreak may occur at percentages of added water of from 250% to as much as 850%, thereby yielding entrapment efficiencies of from 71% to 89.5%. Mathematically, the entrapment efficiency in washing may be expressed by the relationship- In 100+In where In is the percent added water to gel-break.

As an essential feature of the invention, it has been found that there exists a critical balance, within a relatively narrow range of proportional content, between the two basic constituents as stated above, at which the abovedescribed broad gel-range conditions are obtained. In addition, it has been found that when a supplemental ingredient, such as a glycol, is included in the composition, this critical balance condition still pertains, although the relative proportions of ingredients necessary to achieve an optirmum condition of broad gel-range may -be shifted slightly.

Referring now to FIG. 4, a chart is shown herein which the percent added water at gel-break is charted for various relative proportions of ingredients in a three-phase system consisting of a water-insoluble ethoxylated alkylphenol, a water-soluble ethoxylated alkylphenol, and a glycol. For the purpose of preparing this chart, the water-insoluble ethoxylated alkylphenol employed was nonylphenol ethoxylated with 1.5 mols ethylene oxide per mol of nonylphenol, and is present in the test formulations in the amount of three proportional parts. The water-soluble ethoxylated alkylphenol employed was nonylphenol ethoxylated with 9 mols of ethylene oxide per mol of nonylphenol. This material and the glycol ingredient, which was hexylene glycol, were mixed in varying proportions with the three proportional parts of the 1.5 mol ethoxynonylphenol, and the gel-break for each condition of admixture was determined.

Examination of the chart of FIG. 4 reveals that there is a well dened zone within the field of possible formulations employing the three ingredients in which a substantial gel condition is obtained. This same characteristic of gel formation is obtained in formulations of any of the ingredients described and listed above. In the region outside the line 40, no gel condition is obtained at all, while inside the region of gel formation, the value of gel-break rises rapidly and reaches a peak at point 41. Point 41 is generally found on the abcissa of the chart where the glycol content of the composition is zero.

Also shown in FIG. 4 is a line 42 which represents a threshold condition of washability for the above-described family of mixtures. At all points to the left of line 40, the mixtures of ingredients are insoluble in water, even though they may absorb water to forrn thickened or gel-like material. Thus, such water-insoluble compositions cannot be used as water-washable inspection penetrants because residual penetrant on the surfaces of test parts Will not wash clean. The position of this threshold of washability may be altered by altering the ethylene oxide content of the water-insoluble surfactant ingredient in the formulation, as illustrated by line 43. Line 43 represents the threshold of washability of formulations in which the three proportional parts of 1.5 mol ethoxy nonylphenol are replaced with three parts of nonylphenol (with zero ethoxy content). This alteration of the formulation does not shift the position of point 41 to any appreciable degree; however, it is found that a formulation made using nonylphenol and having a gel-break characteristic corresponding to point 41 is now wash removable only with considerable difficulty.

Although .a marginal-washability pentrant or emulsier `formulation such as this, employing nonylphenol as an ingredient, is sometimes desirable and can be successfully used to provide excellent entrapment efciency, extreme care must be taken to insure proper wash removal of the penetrant from test parts. Hence, for practical considerations in handling the material, a characteristic washability threshold close to that illustrated by line 42 is usually to be preferred.

It will be seen that by properly selecting the chemical nature 0f the two or three liquid ingredients which may be included in the compositions of the invention, and by adjusting the ethoxy content of the ethoxylated alkylphenol ingredients, various formulations may be provided which exhibit consistently higher levels of entrapment eiciency and washability characteristics which may be optimum for given operating conditions.

In preparing a testing composition in accordance with the invention, it is preferred that the water-insoluble and water-soluble ethoxylated alkylphenol ingredients be irst mixed together in proportional amounts such that the -mixture is simultaneously washable in water, as determined by a wash-removability test on a flat metal panel or the like, and capable of forming a gel upon the addition of water to the mixture. Where a maximum value for the gel-break is wanted, the relative proportions of the two 9 ethoxylated alkylphenol ingredients may be varied stepwise and tested for the point of gel-break, thus permitting the selection of an optimum formulation as required. Then, if so desired, the glycol ingredient may be added for the purpose of adjusting the initial viscosity of the mixture or for the purpose of extending the volume of the mixture to reduce its cost per unit volume. The final formulation which may be selected by consideration of the optimum balance conditi-on to provide a desired value for gel-break, and of lacceptable viscosity characteristics, and of economic factors, will be one which exhibits a superior entrapment efficiency and stability as compared to conventional water-washable penetrants and emulsifiers.

If the formulation is to be used as an inspection emulsifier, no indicator dye is required, but if it is to be used as an inspection penetrant, an appropriate indicator dye or dyes, either fluorescent or visible color, may be added in accordance with known practices to provide a desired level of flaw detection performance.

Various other ingredients may be added to the formulations of the invention. For example, a volatile material such as methylene chloride may be utilized to lower the viscosity of a penetrant mixture of the invention, and after the penetrant is applied to a test surface, the volatile ingredient will evaporate and leave the applied penetrant in a water-washable condition. Also, various fluorocarbon Freon type materials may be included with the formulations of the invention, thereby acting as aerosol propellants when the product is packaged in spray cans. Inasmuch as the formulations of the invention may act as emulsiers in post-emulsier penetrant processes, as will be described below, and in that connection may tolerate contamination by substantial amounts of oily liquid materials while still retaining a water-washable characteristic, and inasmuch as the formulations may tolerate the addition of large quantitities of water while retaining a stable characteristic of solution or emulsion, as described below, it is, of course, apparent that inexpensive oily liquids, such as mineral solvents, may be used in limited proportional amounts, or substantial amounts of water may be used, for the purpose of extending the formulation and reducing its cost per unit volume, or for other purposes, as for example adjusting the viscosity of the formulation.

The performance characteristics of the testing compositions of the invention depend primarily on the presence in each composition of the two types of ethoxylated alkylphenol constituents. Such performance characteristics may vary, depending upon the molecular structure and the concentration of the particular alkylphenol constituents employed. Generally speaking, the water-soluble ethoxylated alkylphenol constituent imparts to the -composition a positive hydrophilic character; while the waterinsoluble ethoxylated alkylphenol constituent imparts to the composition a positive lipophilic character. Through the use of alkylphenol constituents of suitable molecular structure and in suitable concentrations, testing compositions in accordance with the invention may be obtained, which exhibit any of a wide and continuous range of variable water-solubility characteristics. As a consequence, the practice of the invention enables easy control of the -characteristics of the testing compositions provided, particularly with respect to the water-solubility of the latter.

The glycol constituents of the testing compositions of the invention behave, when used, it is believed, in the nature of coupling agents. The probable action is that of coupling the ethoxylated alkylphenols to water which enters the testing composition during the washing procedure.

The present invention provides for the use of any of the above-described testing compositions as a penetrant flaw tracer liquid in a water-washable type of penetrant inspection process for the testing of test bodies, parts, etc. Such test bodies may be constructed of metal, ceramic, or other material, and are tested for the purpose of detecting extremely small surface discontinuities and sub-surl0 face flaws therein. Preferaby, the part to be tested, or a test surface thereof, is preliminarily cleaned and degreased in conventional manner, such as by using a vapor degreaser or by washing with alcohol.

After the part has been cleaned and degreased, a penetrant flaw tracer liquid formulated in accordance with the invention is then applied either by dipping the part therein or by brushing or spraying of the liquid onto the test surface. Any suitable shape and size of test surface may be employed. The penetrant liquid is allowed to dwell on the test surface preferably for about 5-10 minutes, during which time it penetrates into any micro-cracks or pores in the surface. Excess penetrant is then drained off from the test surface.

After the drainage of the penetrant liquid, the part is washed by flushing thoroughly with water. The washing step is carried out in conventional manner; e.g., by means of a high pressure spray, or by agitation in a tank of water. The water employed during the washing step carries any penetrant liquid remaining on the surface into a stable emulsion, and thus washes the surface free from any oily residues.

Following the washing step, the test surface is immediately inspected for the existence of surface discontinuities, or subsurface flaws, as revealed by the presence therein of the entrapments of dye-containing penetrant liquid. If a fluorescent dye has been employed, the inspection is made under black light in a darkened inspection booth. In cases where the test object is too large to enclose in a booth, a suitable light shield may be employed.

The water-washable penetrant process just described can, if desired, be modified so as to employ a wet development step. In such cases, the penetrant liquid is applied to `the part being tested, and is then drained from said part in the same manner as described above. Said part is thereafter washed in water, also as described above. Following the washing step, the part is dipped in a conventional wet developer which may, for example, consist of a suspension of talc particles in water. The part is then removed frorn the developer and allowed to dry. The wet developer serves to absorb entrapments as they exude from the flaws. As a result, greatly improved brightness of the flaw indications is produced.

Instead of employing a wet developer as described above, a conventional dry developer may be utilized in conjunction with the water-washable penetrant process of the invention. Such a dry developer consists of talc particles, or other similar type of powder in dry form. Also employable is the conventional type of nonaqueous wet developer, which contains alcohol, or some other nonaqueous carrier for the powder.

In accordance with the present invention, there are further provided water-soluble emulsifier compositions, which are particularly adapted for use in the post-emulsier type of penetrant inspection process. Each of the emulsier compositions of the invention comprises the same basic constituents as the water-washable testing compositions already described, with the exception of the indicator dye. Thus, each of said emulsifer compositions comprises a normally liquid water-soluble ethoxylated alkylphenol, and a normally liquid waterinsoluble ethoxylated alkylphenol, and in some cases, a normally liquid glycol may be included in the composition.

In formulating the emulsifier compositions of the invention, the two basic constituents may be chosen and mixed together in the manner already described above and the supplemental glycol ingredient may be included as desired. The same relative proportions of the three constitutents, as already described, are here again ernployed. Since the proportion of indicator dye in the testing compositions is relatively low, the preferred percentage concentration ranges for the testing compositions, as set forth above, are also approximately correct with respect to the emulsifer compositions.

The emulsiier compositions of the invention are employable in a post-emulsier type of penetrant inspection process. In such process, a penetrant flaw tracer liquid which is of the oil-phase post-emulsiiier type is first applied to the test surface, in the same manner as described above in the case of the water-washable type of process. The excess penetrant liquid is then drained from the test surface.

After the drainage of the penetrant liquid, the test surface is treated with one of the emulsier compositions of the invention. The emulsifier composition is applied either by dipping, brushing, or spraying. If the penetrant aw tracer liquid used contains a fluorescent dye, the emulsication step may be carried out under continuous black light inspection, so that examination of the test surface may be made to assure that the emulsiier has been liberally applied over the entire area thereof. The emulsier is allowed to dwell on the test surface for about 2-5 minutes, during which time it mixes with the penetrant liquid on the surface and renders said penetrant liquid soluble in water.

The test surface is then washed in the same manner as already described. Again, the washing step may be carried out under continuous black light inspection to insure that all surface smears of penetrant have been removed. Any residual smears are then cleared away by a local application of emulsilier, and re-Washing. After washing, the test surface is drained, and thereafter inspected for the presence of flaws, in the manner already described.

The post-emulsifier penetrant process just described can, as in the case of the water-washable process, be modified so as to employ a Wet development'step. Here, however, a penetrant liquid is employed consisting of a volatile solvent, such as, perchloroethylene, containing a visible dye indicator. The penetrant liquid is applied to the part being tested in a manner such as described above. Said part is then allowed to drain and dry, with the result that surface deposit of dry dye remains. The part is thereafter immersed in the emulsiiier in the same manner as already set forth above. Following a dwell time in the emulsifier of preferably about one minute, the part is washed in a manner as above described. The part is thereafter dipped in the wet developer, which may, again, consist of a suspension of talc particles in water. The part is then removed from the developer and allowed to dry. Any surface flaws which exist thus become revealed by visible dye indications.

In the process just described, the emulsier enters the surface flaws, carrying the dry dye into solution, and forming aw entrapments of dyed emulsier. At this point, the emulsifier becomes the equivalent of a water-washable penetrant of the invention. The washing step removes the dyed-emulsifier cleanly as a stable emulsion from the surfaces of the part. Said surfaces are thus rendered free from any oily residues. This process is compatible with liquid oxygen, as a result of the fact that deleterious reactions between the oxygen and oily penetrant residues are minimized.

In a process of the invention of either the post-emulsiier or the water-washable type, the washing step consists of progressively diluting the penetrant with water. After water has been added to the penetrant in the amount of about 30%, the mixture increases in viscosity to form a gel-like material. This gel-like condition persists until the proportional amount of added water reaches as much as 250% up to 850%. At this point, a stable emulsion forms, which exhibits no phase separation, even upon extensive dilution up to and beyond dilution ratios of 40 to 1.

As a result of the fact that the penetrant entrapments pass through a phase during the absorption of Water, as just described, such that an extremely high viscosity ensues, said entrapments tend to freeze into position. Consequently, an enhanced stability of the entrapments is provided. While the penetrant entrapments remain washable in water, the rate at which they diffuse into solution is much reduced by virtue of the highly viscous condition. Due to this relatively stable character of the penetrant entrapment, a relatively large number of the entrapments remain available for inspection.

v It has thus been discovered that the water-washable penetrant compositions and the emulsiier compositions of the invention, when employed in a penetrant aw tracer process, exhibit unusual and unexpected advantages in respect of the high level of flaw entrapment eliiciency achieved.

In further regard to the degree of flaw entrapment eiciency obtained, it has been previously pointed out that oil-phase water-washable penetrants of conventional type exhibit poor flaw entrapment efficiency, unless the solubilizing strength of the detergent system employed is just sufficient, and no more, to render the oily component of the penetrant emulsifiable, or washable in water. The compositions of the present invention, in contrast, enable the use of unusually high solubilizing strengths, such as would normally lead to a low flaw entrapment efficiency. Nevertheless, high aw entrapment efficiency is maintained, particularly in view of the abovediscussed viscosity enhancement effects. The high solubilizing strengths of the compositions of the invention assures substantially complete removal of penetrant liquid from the test surfaces, and consequent absence of reactive residues.

As a further unusual and unexpected advantage provided by the compositions of the invention, a high degree of stability of the emulsions formed is achieved, along with the high level of flaw entrapment eiciency. Thus, as has already been pointed out, the emulsions which are formed in conventional penetrant flaw tracer processes tend to be unstable, exhibiting characteristics of phase separation, leading to re-precipitation of non-emulsiiied materials on the surfaces being cleaned; and to possible resultant inter-granular corrosion, or chemical reactivity, particularly if the parts tested are used in liquid oxygen systems. In marked contrast, the emulsions formed through use of the compositions of the present invention exhibit a comparatively high degree of stability. Thus, the emulsions so formed can be diluted up to a ratio of 40:1 or higher, While still maintaining good stability.

Example l A penetrant flaw tracer liquid having the following formulation was prepared:

Nonylphenol V3 parts. Ethoxylated nonylphenol (9 mols ethylene oxide) 11.5 parts. Fluorescent dye (indicator) 1% by weight of the formulation.

The above penetrant liquid, when used in an inspection penetrant process, was wash-removable under a high pressure spray of water and yielded fluorescent indications of flaws at a sensitivity level corresponding to a medium sensitivity post-emulsier type penetrant system.

Example 1I A penetrant -aw tracer liquid having the following formulation was prepared:

Ethoxylated nonylphenol 1.5 mols ethylene oxide) ml 455 Ethoxylated nonylphenol (9 mols ethylene oxide) ml 1400 Methylene chloride ml 1200 Fluorescent indicator dye gms 175 The above penetrant liquid, when used in an inspection penetrant process, may be applied by dipping, brush, airspray, airless-spray, or electrostatic spray. When test parts to which'this material is applied are allowed to drain for A penetrant flaw tracer liquid having the following formulation was prepared:

Parts by volume Ethoxylated octylphenol (10 mols ethylene oxide) 19 Ethoxylated nonylphenol (2 mols ethylene oxide) 7 Visible red dye 1 The above penetrant liquid, when used in a penetrant inspection process, was water-washable, and provided aw entrapments of visible red color.

Example IV A penetrant flaw tracer liquid Was prepared having the following formulation:

Parts by volume Glycerin 10 Ethoxylated dodecylphenol (12 mols ethylene oxide) 20 Ethoxylated nonylphenol (1.5 mols ethylene oxide) 7 Fluorescent dye .1

The above penetrant liquid, when employed in a penetrant inspection process, was water-washable, and provided flaw entrapments which were visible under black light.

Example V A penetrant ilaw tracer liquid having the following formulation was prepared:

Parts by volume Tripropylene glycol 9 Ethoxylated dinonylphenol (12 mols ethylene oxide) 16 Ethoxylated nonylphenol (1.5 mols ethylene oxide) 5 Fluorescent dye .2

The above penetrant liquid was found to be employable in a water-washable penetrant inspection process, and provided flaw entrapments which were visible under black light.

Example VI A penetrant aw tracer liquid was prepared having the following formulation:

Parts by volume Propylene glycol 11 Ethoxylated dodecylphenol (l mols ethylene oxide) 17 Ethoxylated nonylphenol `(1.5 mols ethylene oxide) 6 Visible blue dye 1.5

The above penetrant liquid, when used in a penetrant inspection process, was water-washable, and provided ilaw entrapments of a visible blue color.

Example VII A penetrant Haw tracer liquid having the following formulation was prepared:

Parts by volume Ethylene glycol 8 Ethoxylated dodecylphenol (10 mols ethylene oxide) 16 Ethoxylated dinonylphenol (l mol ethylene oxide) Fluorescent dye 5 The above penetrant liquid, when employed in a penetrant inspection process, was water-washable. The aw entrapements obtained were visible under black light, and the sensitivity in respect of uorescent response was discovered to be unusually high.

Example VIII A penetrant flaw tracer liquid was prepared having the following formulations:

Parts by volume Dipropylene glycol Parts by volume Ethoxylated nonylphenol 10 mols ethylene oxide) 17 thoxylated dodecylphenol (2 mols ethylene oxide) 6 Visible red dye 3 The above penetrant liquid proved to be waterwashable when employed in a penetrant inspection process. The aw entrapments obtained were of visible red color.

Example 1X A penetrant llaw tracer liquid having the following formulation was prepared:

Parts by volume Triethylene glycol 9 Ethoxylated dodecylphenol l2 mols ethylene oxide) 16 Ethoxylated nonylphenol (1.5 mols ethylene oxide) 6 Fluorescent dye 10 The above penetrant liquid was found employable in a water-washable penetrant inspection process. The aw entrapments obtained were visible under black light, and an extremely high sensitivity in respect of fluorescent response was exhibited.

Example X A penetrant flaw tracer liquid was prepared having the following formulation:

Parts by volume Hexylene glycol 10 Ethoxylated dinonylphenol (l0 mols ethylene oxide) 18 Ethoxylated nonylphenol (2 mols ethylene oxide) 6 Visible red penetrant 1.5

The above penetrant liquid, when employed in a penetrant inspection process, was water-washable, and provided tlaw entrapments of visible red color.

As examples of the emulsier compositions of the invention, each of the formulations of Examples I-X was prepared, with the elimination of the dye constituent. Each of the resultant formulations was found suitable for use as the emulsifer in a post-emulsier type of penetrant inspection process.

Example XI An emulsifier composition was prepared having the following formulation:

Gals.

Ethoxylated nonylphenol (10 mols ethylene oxide) 25 Ethoxylated nonylphenol (1.5 mols ethylene oxide) 8.1

The above emulsifier composition was employed in postemulsifer processes, as set forth in Examples XII and XIII below. The above formulation was also modified for the purposes of employment in water-washable penetrant inspection processes, as described in Examples XIV and XV below.

Example XII A penetrant inspection process in accordance with the invention, and of the post-emulsier type, was carried out in the following manner:

An aluminum brake plate casting of conventional design was prelirninarily cleaned and degreased in conventional manner, using an ethylene dichloride degreaser.

The brake plate was then dipped in a tank containing a standard MA-3 oily penetrant liquid meeting the U.S. Air Force Specification MlL-I-25 135C(ASG), and containing a fluorescent indicator consisting of 0.5% each of C.I. Fluorescent Brightening Agent No. 68 and Fluorescent Brightening Agent No. 75. The brake plate was then withdrawn from the tank, and the excess penetrant was allowed to drain oif from the surface thereof. A total dwell-drain time of 10 minutes was employed.

There was then applied over the surface of the brake plate an emulsier composition of the invention in accordance with Example XI. The emulsiiier was applied by means of a dip process of conventional type. The brake 15 plate was allowed to dwell in contact with the emulsiiier for about one minute.

The brake plate was then washed in water by means of a high pressure spray. The washing step was carried out under continuous black light inspection. Excess water was then removed from the brake plate by means of an air hose.

The brake plate was then inspected under black light, and there were revealed a number of brilliantly fluorescent pin-points lof light representing the aws present in the surface of the brake plate.

Example XIII A penetrant process -o-f the post-emulsier type in accordance with the invention, and including a wet development step, was carried out in the following manner:

A test member, again in the form of an aluminum brake plate, was preliminarily cleaned and degreased, as already described in Example XII.

The brake plate was then dipped in a tank containing a penetrant liquid, consisting of perchloroethylene as a volatile solvent, and C.I. Solvent Red 76 as a visible dye indicator dissolved in said solvent in the proportion of 7 pounds per 55 gallon quantity. The brake plate was allowed to dwell in the penetrant liquid fo-r l minutes and was then withdrawn for drainage and drying.

The brake plate was then dipped in an emulsier composition of the invention, in the same manner as described in Example XII. Thereafter, the brake plate was washed in water, also as described in Example XII.

After washing, the brake plate was dipped in a conventional wet developer consisting of a suspension of talc particles in water, said talc particles being present in a concentration of about one-half pound (dry powder form) per gallon of water. The brake plate was then removed from the developer and allowed to dry. There were then lobserved visible dye indications of aws present in the surface of the brake plate.

Example XIV A water-Washable penetrant inspection process in accordance with the invention was carried out in the following manner:

Here again, a brake plate was the test member and was preliminarily cleaned and degreased, as already described in Examples XII and XIII.

The brake plate was then dipped in a tank containing a water-washable penetrant flaw tracer liquid in accordance with the invention. Said penetrant liquid was made up of the formulation of Example XI, said formulation having dissolved therein about pounds of C I. Fluorescent Brightening Agent No. 68, and about 31/2 pounds of C.I. Fluorescent Brightening Agent No. 75. To the formulation there was also added water in the amount of 11.5 gallons in order to provide an adjustment to an optimum level of the viscosity of the mixture.

After the dipping operation, the brake plate was removed froln the tank and allowed to drain. The total dwell-drain time was l0 minutes. The brake plate was then Washed by flushing thoroughly with water, in the manner already described.

Following the washing step, the surface of the brake plate was immediately inspected under black light. Surface aws were then observed, as indicated by the uorescent dye employed.

Example XV The water-washable penetrant inspection process of Example XIV was carried out, being modified so as to include a wet development step. All of the steps up to and including the washing step were carried out, as already described. Thereafter, the brake plate was dipped in a conventional wet developer of the same type as described in Example XIII. The brake plate was then removed from 16 the Wet developer and dried. Upon subsequent inspection of the brake plate under black light, bright fluorescent indications of the surface flaws were exhibited.

Although the invention has been described with reference to particular embodiments thereof, it will be understood that various changes may be made therein without department from the spirit of the invention or the scope of the appended claims.

I claim:

1. A gel-forming water-washable and normally liquid testing composition for use in the detection of surface discontinuities in test bodies, said composition consisting essentially of a normally liquid water-soluble ethoxylated alkylphenol having a concentration within the approximate range of 5585%, and a normally liquid waterinsoluble ethoxylated alkylphenol having a concentration within the approximate range of 15-45 2. A testing composition in accordance with claim I in which said water-soluble ethoxylated alkylphenol has an ethylene oxide content within the approximate range of 7 to 15 mols of ethylene oxide per mol of alkylphenol, and said water-insoluble ethoxylated yalkylphenol has an ethylene oxide content within the approximate range of O to 5 mols of ethylene oxide per mol of alkylphenol.

3. A testing composition in accordance with claim 1 in which at least one =of said ethoxylated alkylphenols is a member selected from the group consisting of ethoxylated diamylphenol, ethoxylated octylphenol, ethoxylated nonylphenol, ethoxylated dinonylphenol, ethoxylated trinonylphenol, ethoxylated decylphenol, ethoxylated didecylphenol, ethoxylated undecylphenol, ethoxylated dodecylphenol, ethoxylated octyldecylphenol.

4. A testing composition in accordance with claim 1 in which at least one of said ethoxylated alkylphenols is a member selected from the group consisting of ethoxylated diamylnaphthol, ethoxylated octylnaphthol, ethoxylated nonylnaphthol, ethoxylated dinonylnaphthol, ethoxylated trinonylnaphthol, ethoxylated octyldecylnaphthol.

S. A testing composition in accordance with claim 1 in which at least one of said ethoxylated alkylphenols is a member selected from the group consisting of ethoxylated diamyl p-p biphenol, ethoxylated octyl p-p' biphenol, ethoxylated nonyl p-p biphenol, ethoxylated dinonyl p-p' biphenol, ethoxylated octyldecyl p-p' biphenol.

6. In the nondestructive testing Iof test bodies for surface discontinuities, the step of applying over the surface of a test body a liquid testing composition in accordance with claim 1.

7. A gel-forming water-washable and normally liquid testing composition for use in the detection of surface discontinuities in test bodies, said composition consisting essentially of a normally liquid water-soluble ethoxylated alkylphenol having a concentration within the .approximate range of 3080%, a normally liquid water-insoluble ethoxylated alkylphenol having a concentration within the approximate range of 10-25%, and a normally liquid water-soluble glycol extender having a concentration within the approximate range of zero to 45% 8. A testing composition in accordance with claim 7 in which at least one of said ethoxylated alkylphenols is a member selected from the group consisting of ethoxylated vdiamylphenol, ethoxylated octylphenol, ethoxylated nonylphenol, ethoxylated dinonylphenol, ethoxylated trinonylphenol, ethoxylated decylphenol, ethoxylated didecylphenol, ethoxylated undecylphenol, ethoxylated dodecylphenol, ethoxylated octyldecylphenol.

9. A testing composition in accordance with claim 7 in which at least one of said ethoxylated alkylphenols is a member selected from the group consisting of ethoxylated diamylnaphthol, ethoxylated octylnaphthol, ethoxylated nonylnaphthol, ethoxylated dinonylnaphthol, ethoxylated trinonylnaphthol, ethoxylated octyldecylnaphthol.

10. A testing composition in accordance with claim 7 in which at least one of said ethoxylated alkylpnenols is a member selected from the group consisting of ethoxylated diamyl p-p biphenol, ethoxylated octyl p-p biphenol, ethoxylated nonyl p-p' biphenol, ethoxylated dinonyl p-p biphenol, ethoxylated octyldecyl p-p biphenol.

11. A testing composition in accordance with claim 7 in which said Water-soluble ethoxylated alkylphenol has an ethylene oxide content Within the approximate range of 7 to 15 mols of ethylene oxide per mol of alkylphenol, and said Water-insoluble ethoxylated alkylphenol has an ethylene oxide content Within the approximate range of Zero to mols of ethylene oxide per mol of alkylphenol.

12. ln the nondestructive testing of test bodies for surface discontinuities, the step of applying over the surface of a test body a liquid testing composition in accordance with claim 7.

13. A gel-forming Water-Washable and normally liquid testing composition for use in the detection of surface discontinuities in test bodies, said composition consisting essentially of a normally liquid Water-soluble ethoxylated alkylphenol having a concentration within the approximate range of 55-85%, a normally liquid Water-insoluble ethoxylated alkylphenol having a concentration within the approximate range of 15-45 .and at least one indicator dye having a concentration Within the approximate range of 0.l-40%.

14. A liquid testing composition in accordance With claim 13 in which said indicator dye is a fluorescent sensitizer.

15. A liquid testing composition in accordance with claim 13 in which said indicator dye is a dye of visible color.

16. In the nondestructive testing of test bodies for surface discontinuities, the step of applying over the surface of a test body of liquid testing composition in accordance with claim 13.

17. A gel-forming Water-washable and normally liquid testing composition for use in the detection of surface discontinuities in test bodies, said composition consisting essentially of a normally liquid water-soluble ethoxylated alkylphenol having a concentration within the approximate range of 30-80%, a normally liquid Water-insoluble ethoxylated alkylphenol having a concentration within the approximate range of 10-25%, a normally liquid water-soluble glycol extender having a concentration within the approximate range of zero to and at least one indicator dye having a concentration within the approximate range of .140%. n

18. A liquid testing composition in accordance with claim 17 in which said indicator dye is a fluorescent sensitizer.

19. A liquid testing composition in accordance with claim 17 in which said indicator dye is a dye of visible color.

20. In the nondestructive testing of test bodies for surface discontinuities, the step of applying lover the sur- :tace of a test body of liquid testing composition in accordance with claim 17.

References Cited UNITED STATES PATENTS 3,282,843 1l/l966 Alburger 252-3012 3,028,338 4/1962 Parker 252 30l.2

HELEN M. MCCARTHY, Primary Examiner. TOBIAS E. LEVOW, Examiner.

R. D. EDMONDS, Assistant Examiner. 

17. A GEL-FORMING WATER-WASHABLE AND NORMALLY LIQUID TESTING COMPOSITION FOR USE IN THE DETECTION OF SURFACE DISCONTINUTIES IN TEST BODIES, SAID COMPOSITION CONSISTING ESSENTIALLY OF A NORMALLY LIQUID WATER-SOLUBLE ETHOXYLATED ALKYLPHENOL HAVING A CONCENTRATION WITHIN THE APPROXIMATE RANGE OF 30-80%, A NORMALLY LIQUID WATER-INSOLUBLE ETHOXYLATED ALKYLPHENOL HAVING A CONCENTRATION WITHIN THE APPROXIMATE RANGE OF 10-25%, A NORMALLY LIQUID WATER-SOLUBLE GLYCOL EXTENDER HAVING A CONCENTRATION WITHIN THE APPROXIMATE RANGE OF ZERO TO 45%, AND AT LEAST ONE INDICATOR DYE HAVING A CONCENTRATION WITHIN THE APPROXIMATE RNGE OF .1-40%.
 18. A LIQID TESTING COMPOSITION IN ACCORDANCE WITH CLAIM 17 IN WHICH SAID INDICATOR DYE IS A FLUORESCENT SENSITIZER. 